1. Field of the Invention
The present invention relates to a surface acoustic wave device wafer level package that packages a surface acoustic wave device according to a wafer level packaging method, and a fabrication method thereof.
2. Description of the Related Art
As an electronic device is developed to be compact and high-efficient, its electronic parts need to also be compact and high-efficient. A surface acoustic wave (SAW) device is generally used as an electronic part such as a filter, a delay line, or an oscillator of an electronic device transmitting and receiving waves, and is also employed as a radio frequency (RF) part in a mobile phone to suppress unnecessary signals. As mobile phones have become significantly compact and high-efficient, the SAW device including package also need be compact and high-efficient. Additionally, as the SAW device has been increasingly used for various purposes, demands for SAW devices have been significantly increasing, and reduction of the manufacturing costs is required.
A filter device, that is, a SAW filter 10, manufactured using a conventional SAW device, will be explained with reference to FIGS. 1A and 1B. As can be seen from the drawings, the SAW filter 10 comprises a ceramics package 11, a cavity 12 formed to be hollow in the package 11, a metal cap 13 to hermitically seal an opening of the cavity 12, and a SAW element 14 packed in the cavity 12. As can be seen in FIG. 1B, the package 11 forms a three layer structure in which three substrates 11a, 11b, and 11c are bonded. An electrode pad 15, a wire pattern 16, and a foot pattern 17 are formed over the substrates 11a, 11b, and 11c. The SAW element 14 is fixed on a bottom portion of the cavity 12 such that a surface with an interdigital transducer (IDT) faces up. The SAW device 14 is electrically connected with the wire pattern 15, which is exposed to an inside of the cavity 12, by a metal wire 18. The metal cap 13 is deposited onto a top surface of the package 11 by binding material 19 such as solder or resin.
The SAW filter 10 with the above configuration has the SAW element 14 that is electrically connected with the package 11 through a wire so as to hermitically seal the SAW element, and the metal cap 13 is deposited onto the top surface of the package 11 so that there is a limit of how compact the SAW filter 10 can be made. As a size of the SAW element 14 gets smaller, manufacturing of the SAW filter 10 becomes more complicated so that the manufacturing cost can increase.
Accordingly, various methods have been developed using wafer level packaging technology to miniaturize the SAW device. Particularly, studies for a SAW device having a SAW element on a wafer, and for a packaging method by binding a packaging cap with a top portion of the SAW device have been developed.